Bobbin fixing device

ABSTRACT

In a bobbin fixing device, a collet type chuck having claw members is mounted to the upper portion of a rotary hollow shaft and a bobbin slip-off preventing member  27  which comprises a substantially U-shaped claw expansion portion having arcuate projection portions for expanding the interval between the above claw members is inserted between the claw members of the above collet type chuck to secure a bobbin to the rotary shaft without fail at the time of winding off a wire material and facilitate the exchange of the bobbin. The claw expansion portion of the bobbin slip-off preventing member is fitted in guide grooves formed in the claw members to expand the interval between the claw members so as to press the upper end portions of the bobbin and rotatably hold the bobbin when the bobbin is to be mounted and holding force is not applied to the bobbin by taking out the bobbin slip-off preventing member when the bobbin is to be exchanged.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a bobbin fixing device for rotatably holding a bobbin for use in a wire winding machine or wire twisting machine.

[0003] 2. Description of the Prior Art

[0004] In the prior art, when a wire material is to be supplied to a wire winding machine or wire twisting machine, it is wound off from a bobbin wound with it by rotating the bobbin. Therefore, a bobbin fixing device for rotatably holding the above bobbin is used. FIGS. 5(a) and 5(b) show a bobbin fixing device 50 of the prior art in which a rotary hollow shaft 55 connected to a fixed shaft 52 by bearings 53 and 54 is situated around the fixed shaft 52 secured in a base 51 and a leaf spring 56 for fixing a bobbin 10 is mounted to the rotary shaft 55 so that the above bobbin 10 can be rotatably held making use of the restoring force of the above leaf spring 56 by mounting the spool core portion 11 of the bobbin 10 to the above rotary shaft 55. More specifically, the position of the lower flange 12 a of the bobbin 10 is restricted by a collar-like positioning plate 57 projecting horizontally from the lower end of the rotary shaft 55 and the inner wall 11 s of the spool core portion 11 of the bobbin 10 is pressed by the leaf spring 56 to generate friction force between the leaf spring 56 and the bobbin 10, thereby preventing the slipping of the bobbin which occurs at the time of winding off the unshown wire material and rotatably holding the bobbin 10.

[0005] Denoted by 58 is a bobbin slip-off prevention pin which is a substantially U-shaped spring member composed of a securing piece 58 a having an arcuate securing portion 58 c at the center and a linear insertion piece 58 b connected to the securing piece 58 a. The slip-off of the bobbin 10 is prevented by inserting the above insertion piece 58 b into an insertion hole 55 b formed in the upper end portion of the rotary shaft 55 slightly above the upper flange 12 b and inserting the securing piece 58 a into a securing groove 55 c formed in the periphery of the rotary shaft 55 at the time of inserting the bobbin 10.

[0006] In the above bobbin fixing device 50 of the prior art, the above bobbin slip-off prevention pin 58 acts as a stopper and simultaneously exerts a force to press slightly the bobbin (10) on to the rubber plate (57 c). Since the bobbin 10 is held only by friction force between the leaf spring 56 and the inner wall 11 s of the spool core portion 11, the spring force of the above leaf spring 56 must be increased to enhance friction force, that is, bobbin holding force in order to prevent the slipping of the bobbin 10. However, as the holding force of this leaf spring 56 is always applied to the bobbin 10, force is needed to exchange the bobbin 10, resulting in a great burden on an operator.

[0007] Further, since the above leaf spring 56 is worn down by friction force generated at the time of winding off the wire material and also exchanging the bobbin 10, it must be exchanged regularly, thereby requiring management and exchange works.

[0008] In view of the above problems of the prior art, it is an object of the present invention to provide a bobbin fixing device which can secure a bobbin to a rotary shaft without fail at the time of winding off a wire material and facilitates the exchange of the bobbin.

SUMMARY OF THE INVENTION

[0009] According to a first aspect of the present invention, there is provided a bobbin fixing device comprising a rotary hollow shaft, having a positioning plate for restricting the position of the lower flange of a bobbin, for accepting the bobbin and a fixed shaft connected to the rotary shaft by bearings, wherein the device further comprises a collet type chuck which is mounted to the upper portion of the rotary shaft and a bobbin slip-off preventing member which is inserted into the space between the claw members of the collet type chuck to expand the interval between the claw members. The position of the lower flange of the bobbin is restricted by the above positioning plate, the claw members are pressed outward by the above bobbin slip-off preventing member to press the upper end portion of the bobbin (more specifically, the upper end portion of the inner wall of the spool core portion) to apply holding force to the bobbin When the bobbin is to be mounted, and holding force is not applied to the bobbin by taking out the above bobbin slip-off preventing member to return the claw members to the original positions when the bobbin is to be exchanged. Thereby, the bobbin can be secured to the rotary shaft securely when the wire material is wound off and the bobbin can be easily exchanged.

[0010] According to a second aspect of the present invention, there is provided a bobbin fixing device, wherein the bobbin slip-off preventing member is a spring member composed of a claw expansion portion having tapered portions for expanding the interval between the claw members and securing portions for sandwiching the rotary shaft from both sides. Therefore, the expansion of the interval between the claw members and the slipping and slip-off of the bobbin which occurs at the time of winding off the wire material can be carried out by one member.

[0011] According to a third aspect of the present invention, there is provided a bobbin fixing device, wherein the bobbin slip-off preventing member is a spring member composed of (1) a substantially U-shaped claw expansion portion having arcuate projecting portions projecting outward for expanding the interval between-the claw members at the center of each side, (2) substantially ring grip portions, connected to the both ends of the claw expansion portion, for holding the bobbin slip-off preventing member, and (3) securing portions, extending from the grip portions in parallel to the claw expansion portion, for sandwiching the rotary shaft from both sides.

[0012] According to a fourth aspect of the present invention, there is provided a bobbin fixing device, wherein guide grooves for accepting the bobbin slip-off preventing member are formed in the inner walls of the collet type chuck. This facilitates the mounting of the bobbin slip-off preventing member.

[0013] According to a fifth aspect of the present invention, there is provided a bobbin fixing device, wherein cut-out portions are formed in the upper portions of the rotary shaft so that the upper portions of the claw members are exposed from the respective cut-out portions to fix the bobbin.

[0014] The above objects, features and advantages of the present invention will become apparent from the following description when taken in conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIGS. 1(a) and 1(b) are diagrams of a bobbin fixing device according to the most preferred embodiment of the present invention.

[0016] FIGS. 2(a) and 2(b) are diagrams of the bobbin fixing device according to the most preferred embodiment of the present invention;

[0017] FIGS. 3(a) to 3(c) are diagrams showing a method of attaching and detaching a bobbin according to the most preferred embodiment of the present invention;

[0018] FIGS. 4(a) and 4(b) are diagrams of another example of a bobbin slip-off preventing member according to the present invention; and

[0019] FIGS. 5(a) and 5(b) are diagrams showing the constitution of a bobbin fixing device of the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Preferred embodiments of the present invention will be described hereinunder with reference to the accompanying drawings.

[0021] FIGS. 1(a) and 1(b) and FIGS. 2(a) and 2(b) are front views and side views of a bobbin fixing device 20 according to the most preferred embodiment of the present invention. In these figures, reference numeral 21 is a block shaped base being formed as a part of the shaft for mounting the bobbin fixing device 20 to the fixed block 31 of a bobbin mounting unit such as a wire twisting machine, 22 a fixed shaft integrated with the base 21 processed to a stepped shape, and 23 a rotary hollow shaft connected to the above fixed shaft 22 by bearings 24 and 25 around the above fixed shaft 22. A collar-like positioning plate 23 a projecting horizontally from the periphery of the above rotary shaft 23 is situated at the lower end of the rotary shaft 23, and a projecting portion 23 b formed on the rear side of the positioning plate 23 a is inserted into a guide groove 32 m formed in the rotary base 32 of the above bobbin mounting unit.

[0022] Denoted by 26 is a collet type chuck mounted to the upper portion of the above rotary shaft 23, and 27 a bobbin slip-off preventing member for expanding the interval between the claw members 26 a and 26 b of the above collet type chuck 26.

[0023] The claw members 26 a and 26 b of the collet type chuck 26 comprise peripheral portions 26 m secured to the peripheries of cylindrical collars 26 c by snap rings 26 d in such a manner that they face each other and vertical pieces 26 n which project upward from the above snap rings 26 d and are smaller in diameter than the above peripheral portions 26 m, respectively, arcuate guide grooves 26 k for accepting the claw expansion portion 27 a of the bobbin slip-off preventing member 27 which will be described hereinafter are formed in the respective inner walls of the above vertical pieces 26 n, and arcuate projection portions 26 t are situated below the grooves 26 k. As shown in FIGS. 2(a) and 2(b), the peripheral portions 26 m of the above claw members 26 a and 26 b are exposed from cut-out portions 23W formed in the periphery of the rotary shaft 23, predetermined spaces S are formed between the peripheries of the above vertical pieces 26 n and the inner wall 23 s of the above rotary shaft 23, and the peripheries of the above projection portions 26 t are inscribed in the inner wall 23 s below the above respective cut-out portions 23W. Therefore, the claw members 26 a and 26 b can be projected toward the outside of the rotary shaft 23 from the cut-out portions 23W by inclining the vertical pieces 26 n and 26 n of the claw members 26 a and 26 b toward the inner wall 23 s of the rotary shaft.

[0024] The bobbin slip-off preventing member 27 is a spring member composed of a substantially U-shaped claw expansion portion 27 a having arcuate projection portions 27 p projecting outward for expanding the interval between the claw members 26 a and 26 b at the center of each side, substantially ring grip portions 27 b for holding the bobbin slip-off preventing member 27, which are connected to the respective ends of the claw expansion portion 27 a, and securing portions 27 c, extending from the grip portions 27 b in parallel to the above claw expansion portion 27 a, for sandwiching the above rotary shaft 23 from both sides. When the above claw expansion portion. 27 a having the projection portions 27 p is fitted in the centers of the guide grooves 26 k of the collet type chuck 26, the above securing portions 27 c are also secured in securing grooves 23 k formed in the periphery of the rotary shaft 23.

[0025] A description is subsequently given of a method of attaching and detaching a bobbin 10 by the above bobbin fixing device 20 with reference to FIGS. 3(a) to 3(c). In FIGS. 3(a) to 3(c), sectional views and plan views of the bobbin fixing device 20 are shown different in size to make the movements of the claw members 26 a and 26 b easy to be understood.

[0026] First, the spool core portion 11 of the bobbin 10 is mounted to the rotary shaft 23 until its lower flange 12 a is contacted to the positioning plate 23 a (see FIGS. 1(a) and 1(b)). Since the rotary shaft 23 has no leaf spring which becomes a resistor at the time of mounting the bobbin in this embodiment unlike the prior art, the bobbin 10 can be easily set on the rotary shaft 23.

[0027] As shown in FIG. 3(a), the claw expansion portion 27 a of the bobbin slip-off preventing member 27 is inserted into the collet type chuck 26 from near the guide grooves 26 k of the collet type chuck 26 by holding the grip portions 27 b and 27 b of the bobbin slip-off preventing member 27. At this point, by inserting the securing portions 27 c into the securing grooves 23 k of the rotary shaft 23, the above claw expansion portion 27 a can be smoothly guided into the guide grooves 26 k. The spaces S between the peripheries of the vertical pieces 26 n and 26 n and the inner wall 23 s of the rotary shaft 23 are maintained at the same predetermined value as that before the insertion of the bobbin slip-off preventing member 27 until the projection portions 27 p of the claw expansion portion 27 a reach the guide grooves 26 k.

[0028] Since the above projection portions 27 p project outward in an arcuate form when the projection portions 27 p of the claw expansion portion 27 a reach the guide grooves 26 k, as shown in FIG. 3(b), the claw members 26 a and 26 b begin to be inclined outward with contact points A between the projection portions 27 p and the inner walls of the vertical pieces 26 n and 26 n of the claw members 26 a and 26 b as the points of a lever where force is applied and contact points between the claw members 26 a and 26 b and the inner wall of the rotary shaft 23 as fulcrums. That is, the claw members 26 a and 26 b are pressed outward and the top portions of the peripheral portions 26 m of the above inclined claw members 26 a and 26 b project from the rotary shaft 23, whereby force for pressing slightly the bobbin 10 downward is applied to the upper end of the spool core portion 11 of the above mounted bobbin 10 and as a result, a frictional force is produced between the rubber plate (23 c) and bottom face of the bobbin (10).

[0029] As shown in FIG. 3(c), the interval between the claw members 26 a and 26 b is expanded by inserting the bobbin slip-off preventing member 27 until the tops of the projecting portions 27 p of the claw expansion portion 27 a reach the centers of the claw members 26 a and 26 b and the securing portions 27 c are completely fitted in the securing grooves 23 k to fix the collet type chuck 26.

[0030] That is, since the position of the lower flange 12 a of the bobbin 10 is restricted by the positioning plate 23 a and the top of the bobbin 10 is pressed by the above inclined claw members 26 a and 26 b, the bobbin 10 can be secured to the rotary shaft 23 without fail. Further, as the bobbin holding force of the collet type chuck 26 is about 10 times larger than the bobbin holding force of a leaf spring in the prior art according to the principle of the behavior of the collet, the bobbin 10 does not slip off at all. Consequently, the bobbin fixing device 20 of the present invention can increase the rotation speed of the bobbin 10.

[0031] Since the claw members 26 a and 26 b are not pressed (state shown in FIG. 3(a)), that is, no force is applied to the bobbin 10 when the bobbin slip-off preventing member 27 is taken out to exchange the bobbin 10, the bobbin 10 can be easily removed from the rotary shaft 23.

[0032] That is, since this embodiment has no member for generating friction at the time of attaching and detaching the bobbin, such as a leaf spring in the prior art, when the bobbin 10 is mounted to the rotary shaft 23 or removed from the rotary shaft 23, no load is applied to the bobbin 10 except the weight of the bobbin, thereby making it possible to greatly reduce the work load of attaching and detaching the bobbin 10.

[0033] Also as the work of exchanging a leaf spring in the prior art can be omitted, the work efficiency can be improved.

[0034] Thus, in the bobbin fixing device 20 of the most preferred embodiment of the present invention, the collet type chuck 26 having the claw members 26 and 26 b is mounted to the upper portion of the rotary hollow shaft 23 having the positioning plate 23 a for restricting the position of the lower flange 12 a of the bobbin 10, and the bobbin slip-off preventing member 27 which comprises a substantially U-shaped claw expansion portion 27 a having arcuate projection portions 27 p for expanding the interval between the above claw members 26 a and 26 b can be inserted into and removed from the space between the claw members 26 a and 26 b of the above collet type chuck 26. Therefore, when the bobbin 10 is mounted, the position of the lower flange 12 a of the bobbin 10 is restricted by the above positioning plate 23 a and the claw expansion portion 27 a of the above bobbin slip-off preventing member 27 is fitted into the guide grooves 26 k of the claw members 26 a and 26 b to press the claw members 26 a and 26 b outward, thereby pressing the upper end of the bobbin 10 so that the above bobbin 10 can be rotatably held. Since holding force can be prevented from being applied to the bobbin 10 by taking out the above bobbin slip-off preventing member 27 at the time of exchanging the bobbin 10, the bobbin 10 can be secured to the rotary shaft without fail at the time of winding off the wire material and the bobbin can be easily exchanged, thereby making it possible to greatly reduce the work load of attaching and detaching the bobbin 10.

[0035] The shape of the above bobbin slip-off preventing member is not limited to that of the above embodiment and may be any shape if it can expand the interval between the claw members 26 a and 26 b of the above collet type chuck 26. The projection portions 27 p of the claw expansion portion 27 a may be tapered such that the interval therebetween increases toward a direction opposite to the insertion direction.

[0036] The claw expansion portion 27 a and the securing portions 27 c may be formed as separate units but they are preferably integrated together as a single unit because the claw expansion portion 27 a can be set without fail and this setting work is easy.

[0037] Since the rotary shaft 23 can be held from both sides more securely by using a bobbin slip-off preventing member 37 which comprises securing portions 37 c having arcuate portions 37 q and 37 q inscribed in the rotary shaft 2 as shown in FIGS. 4(a) and 4(b), the claw expansion portion 27 a can be set more securely.

INDUSTRIAL FEASIBILITY

[0038] As described above, according to the present invention, the collet type chuck is mounted to the upper portion of the rotary shaft to which the bobbin is mounted, the claw members of the collet type chuck are pressed outward by the above bobbin slip-off preventing member to press the upper end of the bobbin to apply holding force to the above bobbin when the bobbin is to be mounted, and holding force is not applied to the bobbin by removing the above bobbin slip-off preventing member to return the above claw members to the original positions when the bobbin is to be exchanged. Therefore, the bobbin can be secured to the rotary shaft without fail at the time of winding off the wire material and the bobbin can be easily exchanged. 

What is claimed is:
 1. A bobbin fixing device comprising a rotary hollow shaft, having a positioning plate for restricting the position of the lower flange of a bobbin, for accepting the bobbin and a fixed shaft connected to the rotary shaft by bearings, wherein the device further comprises a collet type chuck which is mounted to the upper portion of the rotary shaft and a bobbin slip-off preventing member which is inserted into the space between the claw members of the collet type chuck to expand the interval between the claw members.
 2. The bobbin fixing device of claim 1, wherein the bobbin slip-off preventing member is a spring member composed of a claw expansion portion having tapered portions for expanding the interval between the claw members and securing portions for sandwiching the rotary shaft from both sides.
 3. The bobbin fixing device of claim 2, wherein the bobbin slip-off preventing member is a spring member composed of (1) a substantially U-shaped claw expansion portion having arcuate projecting portions projecting outward for expanding the interval between the claw members at the center of each side, (2) substantially ring grip portions, connected to the both ends of the claw expansion portion, for holding the bobbin slip-off preventing member, and (3) securing portions, extending from the grip portions in parallel to the claw expansion portion, for sandwiching the rotary shaft from both sides.
 4. The bobbin fixing device of any one of claims 1 to 3, wherein guide grooves for accepting the bobbin slip-off preventing member are formed in the inner wall of the collet type chuck.
 5. The bobbin fixing device of any one of claims 1 to 4, wherein cut-out portions are formed in the upper portions of the rotary shaft so that the upper portions of the claw members are exposed from the respective cut-out portions to fix the bobbin. 